ALUMINA. 



981 



CLINTONITE. 



[In honour of the late Governor De Witt Clinton.] 



Bronzite. Shepard. — Seybertite, Clemson, Dana, Mohs App. — Holmesite. Thomson. — Rhomboedriacber 



Perl-Glimmer. Mohs. 



J"'?- '■'*• Description. Colour copper-red, reddish brown, yellowish brown 



and reddish white. Streak yellowish grey. It occurs imperfectly 

 crystallized, also in foliated masses. Primary form an oblique rhom- 

 bic prism. Fig. 374. M on M' about 94°. Cleavage parallel with 

 planes tangent to the angles of the base, perfect ; with the primary 

 faces imperfect {Breithaupt). Lustre metallic pearly. Opaque to 

 translucent ; in thin laminae, sometimes transparent. Hardness from 

 4 . to 4 . 5. Specific gravity from 3 . 07 to 3 . 1 0. Infusible alone by 

 the blowpipe ; with carbonate of soda and borax, it melts into a trans- 

 parent white pearl. When reduced to an impalpable powder, it is 

 attacked by acetic, nitric, muriatic and sulphuric acids (Clemson). 



This mineral resembles some varieties of mica, but it is with difficulty separable into la- 

 minae, and these lamina2 are scarcely flexible even when very thin. It is also harder than 

 mica. From bronzite it differs entirely in its chemical composition. 



Composition. This mineral has been analyzed both by Mr. Clemson and Dr. Thomson, 

 with somewhat different results. These are as follows : 



Silica 17.00 19.35 



Alumina 37.60 44.75 



Magnesia 24.30 9.05 



Lime, 10.70 11.45 



Protoxide of iron, 5,00 



Water, 3,60* 4.55 



Peroxide of iron, 4.80 



Zirconia, .. 2.05 



Oxide of manganese, ...^ 1,35 



Fluoric acid, 0.90t 



LOCALITIES. 



Orange County. The present mineral has hitherto been found only near the village of 

 Amity, and about a mile southwest ; at one of which localities, it occurs in calcareous spar ; 

 and at the other, in serpentine and white limestone. It is associated with spinelle, a peculiar 

 variety of talc, and some other crystalline minerals. Dr. Horton remarks that it often c»m- 



* Clemson. Amerkan Jmmal of Sdmce. XXIV. 171. 



MiN. — Part II, 



+ Thomson. Ibid. XXXI. 170. 



46 



